diff --git a/control_plane.go b/control_plane.go
index 1cedfec..c0febf0 100644
--- a/control_plane.go
+++ b/control_plane.go
@@ -15,6 +15,7 @@
 package opensergo
 
 import (
+	"log"
 	"os"
 	"sync"
 
@@ -130,6 +131,7 @@ func (c *ControlPlane) handleSubscribeRequest(clientIdentifier model.ClientIdent
 			err = c.sendMessageToStream(stream, request.Target.Namespace, request.Target.App, kind, nil, status, request.RequestId)
 			if err != nil {
 				// TODO: log here
+				log.Printf("sendMessageToStream failed, err=%s\n", err.Error())
 			}
 			continue
 		}
@@ -152,6 +154,7 @@ func (c *ControlPlane) handleSubscribeRequest(clientIdentifier model.ClientIdent
 			err = c.sendMessageToStream(stream, request.Target.Namespace, request.Target.App, kind, dataWithVersion, status, request.RequestId)
 			if err != nil {
 				// TODO: log here
+				log.Printf("sendMessageToStream failed, err=%s\n", err.Error())
 			}
 		}
 	}
diff --git a/pkg/controller/crd_watcher.go b/pkg/controller/crd_watcher.go
index 7017420..6316ffb 100644
--- a/pkg/controller/crd_watcher.go
+++ b/pkg/controller/crd_watcher.go
@@ -148,10 +148,10 @@ func (r *CRDWatcher) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Resu
 	}
 
 	app := ""
-	hasAppLabel := true
 	if crd != nil {
 		// TODO: bugs here: we need to check for namespace-app group, not only for app.
 		// 		 And we may also need to check for namespace change of a CRD.
+		var hasAppLabel bool
 		app, hasAppLabel = crd.GetLabels()["app"]
 		appSubscribed := r.HasAnySubscribedOfApp(app)
 		if !hasAppLabel || !appSubscribed {
diff --git a/pkg/transport/grpc/server.go b/pkg/transport/grpc/server.go
index 8e1f76c..fc43adc 100644
--- a/pkg/transport/grpc/server.go
+++ b/pkg/transport/grpc/server.go
@@ -16,14 +16,15 @@ package grpc
 
 import (
 	"fmt"
+	"io"
+	"log"
+	"net"
+
 	"github.com/opensergo/opensergo-control-plane/pkg/model"
 	trpb "github.com/opensergo/opensergo-control-plane/pkg/proto/transport/v1"
 	"github.com/opensergo/opensergo-control-plane/pkg/util"
 	"go.uber.org/atomic"
 	"google.golang.org/grpc"
-	"io"
-	"log"
-	"net"
 )
 
 const (
@@ -117,8 +118,10 @@ func (s *TransportServer) SubscribeConfig(stream trpb.OpenSergoUniversalTranspor
 			// This indicates the received data is a response of push-failure.
 			if recvData.Status.Code == CheckFormatError {
 				// TODO: handle here (cannot retry)
+				log.Println("Client response CheckFormatError")
 			} else {
 				// TODO: record error here and do something
+				log.Printf("Client response NACK, code=%d\n", recvData.Status.Code)
 			}
 		} else {
 			// This indicates the received data is a SubscribeRequest.
@@ -150,7 +153,6 @@ func (s *TransportServer) SubscribeConfig(stream trpb.OpenSergoUniversalTranspor
 		}
 
 	}
-	return nil
 }
 
 func newTransportServer(connectionManager *ConnectionManager, subscribeHandlers []model.SubscribeRequestHandler) *TransportServer {
diff --git a/pkg/util/format_util.go b/pkg/util/format_util.go
index 55a3dc3..a8d2b4f 100644
--- a/pkg/util/format_util.go
+++ b/pkg/util/format_util.go
@@ -15,9 +15,10 @@
 package util
 
 import (
-	pb "github.com/opensergo/opensergo-control-plane/pkg/proto/fault_tolerance/v1"
 	"strconv"
 	"strings"
+
+	pb "github.com/opensergo/opensergo-control-plane/pkg/proto/fault_tolerance/v1"
 )
 
 func Str2MillSeconds(timeStr string) (int64, error) {